Light Emitting Diodes (LEDs) have many advantages over conventional light sources, such as incandescent, halogen and fluorescent lamps. These advantages include longer operating life, lower power consumption, and smaller size. Consequently, conventional light sources are increasingly being replaced with LEDs in traditional lighting applications. As an example, LEDs are currently being used in flashlights, camera flashes, traffic signal lights, automotive taillights and display devices.
Two prevalent types of LED form factors are surface-mount LEDs and thru-hole LEDs. Surface-mount LEDs are desirable for applications which require a low LED profile. Among the various packages for surface-mount LEDs, an LED package of interest is the Plastic Leaded Chip Carrier (PLCC) package. Surface mount LEDs in PLCC packages may be used, for example, in automotive interior display devices, electronic signs and signals, and electrical equipment.
While the PLCC package does offer a relative low profile as compared to its thru-hole counterpart, currently available PLCC packages cannot simultaneously provide high contrast and high brightness. Specifically, a PLCC package that is designed to provide high contrast (e.g., by using a black plastic as its housing) does not generally provide high brightness because the plastic used for the housing absorbs light rather than reflects light. Conversely, a PLCC package that is designed to provide high brightness (e.g., by using a white plastic as its housing) does not generally provide high contrast.
It should also be noted that a thru-hole LED is almost always brighter than a PLCC package, regardless of whether a black or white plastic is used for the housing. This is because the thru-hole LED typically has a metal-plated reflector cup whereas the reflector cup in a PLCC package is traditionally plastic, which is not as reflective as the metal use in thru-hole LEDs.
To date, there is no known LED package that combines the low profile nature of a PLCC package as well as simultaneously achieves high contrast and brightness.